I've been looking for some baltic birch for my upcoming enclosure, but have had some trouble looking for some. I found a lumber yard that has a 5x5 sheet of .75" baltic birch for 46 bucks, but he stated that the interior side has voids, but not the front panel. Is that safe to use or what? This will be my first attempt on building an sealed enclosure for a 18" W6. I also found this "Hanks hardware place that has baltic birch, but it's 9 ply .75" 5x5 for 26 bucks. I've heard it's good to go with 13 ply birch, so that makes me want to steer clear from the 9 ply birch. feedback would be great, thanks.